Device in motor saws



July 31, 1945. c. G. HARD AF SEGERSTAD 2,380,

DEVICE IN MOTOR SAWS Filed Dec. 31, 1941 2 Sheets-Sheet l July 31, 1945. c. G. HARD AF SEGERSTAD 80,7 3

DEVICE IN MOTOR SAWS 2 Sheets-Sheet 2 Filed Dec. 31, 1941 Patented July 31, 1945 DEVICE IN MOTOR SAWS Carl Gustaf Hard af Segerstad, Sandviken,

Sweden,

assignor to Sandvikens Jernverks Aktiebolag, Sandviken, Sweden Application December 31, 1941, Serial No. 425,223

In Sweden November 22, 1940 2 Claims.

The present invention relates to a device in such motor saws for felling trees, crosscutting logs and the like as consist of an endless chain composed by a plurality of saw elements and adapted to run around two wheels located at either end of the motor saw, one of said wheels being motor driven and serving as driving member for the chain, the latter being guided by a guide rail provided between the wheels. The invention is substantially characterized in that the .saw element consists of two plates provided right opposite each other on either side of intermediate bodies, one of the plates having saw teeth while the other serves as supporting plate, the plates being further arranged alternately in such a manner that every second plate in one row serves as supporting plate while the other are saw plates.

saw relatively to the plane of the chain and the guide rail. In both positions the aggregate can be locked relatively to the casing 6.

The endless saw chain may consist of an endless steel cord ll, to which a plurality of saw eleinterstice, which is intended for the steel cord ll.

' Some embodiments of the invention are illustrated in the accompanying drawings, in which Fig. 1 is a side view of the motor saw,

Fig; 2 is a top view .of the same,

Fig. 3 shows a detail on a larger scale of the chain Fig. 4 is a cross section taken on the line IVIV in Fig. 3,

Fig. 5 shows a detail of the chain,

Fig. 6 is a cross section taken on the line VIV'I in Fig. 5,

Fig. '7 shows a further. detail of the chain, and I Fig. 8 is a longitudinal section taken on the line VI1IVIII in Fig. 7.

Referring to the drawings, reference numeral I designates the motor aggregate with its fueltank and with two handles 2 fixed to it. Of course an electro-motor may be used instead, in which case the fuel-tank is dispensed with. The motor aggregate is turnably connected with the rest of the saw. The latter consists of an endless chain running around two wheels 3 and 4 provided at the ends of the motor saw. One of the wheels is given the shape of a chain wheel and connected with the motor shaft by means of a disengaging device 5. The chain wheel 3 as well as the necessary driving members are enclosed in a casing 6. The other wheel i enclosed in a protective casing I. Between e wheels there is provided a guide rail 8, which is fixed to the casings 6 and I by means of suppo ing elements 9 and Ill. The guide rail 8 may p eferably be provided with longitudinal ridges II and I: so as to increase the stiffness of the rail. In order to control the tension of the chain there is provided at the casing a stretching device l3, which may also serve as a handle. The motor aggregate can be turned 90 around the longitudinal axis of the. motor shafts.

By means of a turnable locking peg l9 or the like, which, for example, is eccentrically mounted, the saw element is fixed to the cord. That edge of the body l8 which contacts with the steel cord is rounded off so as to facilitate its running around the chain wheel. Moreover, said body is provided with a recess 20 corresponding to the teeth of the chain wheel and intended for engagement with the same. The plates [5 and I6 have such length that they partly embrace the guide rail 8, the latter thereby supporting and guiding the saw elements.

The endless chain may also consist of saw elements only, which are connected with one another by means of links 2|. See Figs. 5 and 6. In this case the saw elements enclose only one intermediate body 22, the latter being provided with recesses for the links and the teeth of the chain wheel. The upper surface of the intermediate body may be formed so as to serve as dust removing member. The shafts 23 and 24 of the link are preferably locked by means of a plate 25 having an aperture 26 to be engaged by a tool when the plate is to be removed. Figs. 7 and 8 show another way of locking the link These shafts have a. varying diameter and are locked at the smallest end 21 by means of a plate 28 which is inserted into a recess in one of the plates enclosing the intermediate body. The plate 28 may be fixed by means of a screw 29 which is preferably secured by means of a centre-mark.

Thanks to the device described the motor saw differs from other saws operating according to the same chain principle by a considerably greater output of work at the same power consumption and a. decrease of weight amounting to 20-25%. This is of importance in portable motor saws with total weights of 25-30 kg. In

addition to its low weight and its lower operat ing costs the device according to the invention involves also the advantage that the saw teeth may be punched, sharpened and set according to the same principles as in usual saws. Moreover. the device according to the invention needs a smaller applying iorce relatively to the working piece than common saw types, the saw being thereby more easily handled and less tiring in operation.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a motor driven cutting chain, a plural-.

ity of saw elements each including, an intermediate flat body, plates arranged on opposite sides of said body, each body and the related plates guide and one or the plates at the opposite end 01 said body being extended beyond the other plate and provided with saw teeth. said flat body extending across the entire width of each plate adjacent the base 01' the saw teeth, the first mentioned end of said body being disposed to move in proximity with the edge of said guide.

2. A motor driven cutting chain as claimed in claim 1, wherein said body is divided into two spaced parts, a flexible coupling membervextending through the spaces between the bo y parts and means carried by said plates for engaging and clamping said flexible .member against the intermediate body.

CARL GUSTAF A! BEGERBTAD. 

